Over the years, I’ve seen people fueling their cars at gas stations while the tanker truck is making a fuel delivery – it makes me cringe. Some of them, I’m sure, are eager to be getting the freshest gasoline, straight off the truck.

It’s not a good idea. While gasoline does have a shelf life of a month or two, you should try to avoid filling up your car right after the fuel has been dropped off at the station.

Why, you ask?

When the tanker truck dumps new fuel into the big underground storage tank at the gas station, it stirs up water and sediment that has collected at the bottom of the tank. While most gas stations filter the fuel you pump, crud can get past the filters and into your car. Waiting a while after the delivery allows the everything to settle back down where it belongs.

Depending how much crud gets in your car’s gas tank, it can cause all sorts of issues. Your car might run bad until your next fill-up, your check engine light might come on, or your car could stop running entirely.

Some cars are more sensitive than others. I’ve owned a few where “bad gas” would render them barely running after driving less than a mile from the pump.

It’s good if the crud gets caught by your fuel filter, although it will shorten the filter’s life. If enough crud clogs the filter completely, the car stops: when no fuel gets to the engine, it can’t run. While it is highly unlikely that one filling of dirty gas will totally clog a brand new fuel filter, most of us are not driving around with brand new fuel filters. In fact, a lot of folks don’t even think about changing their fuel filter. (We’ll cover this in another posting.)

Obviously, you won’t always know if a fuel delivery truck just left your gas station. That’s OK. You can’t avoid every issue relating to bad fuel, but minimizing your exposure when you can helps.

So, next time you see the tanker truck parked at your favorite gas station, delay your fill-up or go to another gas station this time. Doing so might save you a trip to see your mechanic.

I’ll share more useful information about gasoline in future postings. Check back often!